Speed up builds of horizon slowed down by recent upstream change
Speed up builds of horizon slowed down by recent upstream change

Builds of horizon needlessly ran many compilemessages iterations for
core horizon parts because of using horizon's manage.py in a loop.
The behavior was caused by recent upstream change ([1]).

It caused CentOS source builds to take too long time and time out in CI.

This patch switches to using django-admin.

[1] https://opendev.org/openstack/horizon/commit/4e911e2889ebe7f0a577a0323649dceb9cef363c

Change-Id: I737f80566dd263ed291e215968ec72a95ad41a5f
Signed-off-by: Radosław Piliszek <8759e5988b55949fdf66960d1c0fc9651a951f3b@gmail.com>

openstack/kolla,stackforge/kolla,rahulunair/kolla,stackforge/kolla,stackforge/kolla,openstack/kolla,rahulunair/kolla